1. Field of the Invention
The present invention relates to surgical staplers and, more particularly to surgical staplers for use in endoscopic and laparoscopic procedures.
2. Discussion of the Prior Art
Laparoscopic and endoscopic surgical procedures are minimally invasive procedures in which operations are carried out within the body by means of elongated instruments inserted through small entrance openings in the body. The initial opening in the body tissue to allow passage of the endoscopic or laparoscopic instruments to the interior of the body may be a natural passageway of the body, or it can be created by a tissue piercing instrument such as a trocar. With the aid of a cannula assembly inserted into the opening, laparoscopic or endoscopic instrumentation may then be used to perform desired surgical procedures.
Laparoscopic and endoscopic surgical procedures generally require that any instrumentation inserted in the body be sealed, i.e. provisions must be made to ensure that gases do not enter or exit the body through the instrument or the entrance incision so that the surgical region of the body, e.g. the peritoneum, may be insufflated. Mechanical actuation of such instruments is for the most part constrained to the movement of the various components along a longitudinal axis with means provided to convert longitudinal movement to lateral movement where necessary. Because the endoscopic or laparoscopic tubes, instrumentation, and any required punctures or incisions are relatively narrow, endoscopic or laparoscopic surgery is less invasive and causes much less trauma to the patient as compared to procedures in which the surgeon is required to cut open large areas of body tissue.
Surgical fasteners or staples are often used to join body tissue during laparoscopic and endoscopic procedures. Such fasteners can have a pair of legs joined by a backspan and are typically set into the body by means of an elongated instrument which crimps the fastener legs to secure the fastener and tissue.
Various types of stapling instruments have been known for fixing staples to body tissue. Generally, the staples have been applied by using instruments having an anvil and an ejector mechanism for driving the legs of a staple through the tissue and against the anvil for deforming the legs into a "B" shape or the like. An example of such a stapler having an anvil is disclosed in U.S. Pat. No. 4,665,916. An example of a surgical stapler having an anvil and adapted for endoscopic use is disclosed in U.S. Pat. No. 5,040,715. Although these and other various types of instruments are useful for driving the legs of the staple through tissue, there are times when it is not desirable, necessary or practical to drive the legs of the staple through the body tissue in order to affix a staple. For example, when applying a purse string to tissue, as in an end to end anastomosis procedure, it is not desirable or necessary to staple through tissue, but to affix the staples to the tissue.
In cases where a purse string is to be applied to a tubular section of tissue, known stapling instruments have been rather cumbersome and complex in order to provide an anvil against which the staples can be deformed. See, for example, U.S. Pat. No. 4,749,114 and 4,773,420. An anvilless surgical stapler for use in open surgery and a method of affixing a staple to tissue without completely piercing the tissue is disclosed in U.S. Pat. No. 4,821,939 and is incorporated herein by reference. While this anvilless stapler has found success in applying purse strings in open surgery, such a stapler is not properly configured and dimensioned to be used in endoscopic or laparoscopic procedures.
Accordingly, there is a need for an endoscopic surgical stapler adapted for use in confined areas. There is also a need for an anvilless surgical stapler capable of endoscopically applying staples to body tissue. There is also a need for an endoscopic surgical stapler for applying a purse string to body tissue. Additionally, there is a need for an endoscopic surgical stapling instrument capable of applying a purse string to body tissue, wherein the staples secure the string element to body tissue without piercing the tissue with the legs of the staples.